Fluid flow machine

ABSTRACT

The invention concerns a fluid flow machine having a support member, a plurality of angularly spaced-apart blades each of which is mounted in the support member for limited pivotal movement, and frangible force-transmitting means which interconnect adjacent blades so as normally to restrain the blades against such pivotal movement, the frangible forcetransmitting means breaking when subjected to a force exceeding a predetermined value.

United States Patent Palfreyman et al.

[ Feb. 8, 1972 [54] FLUID FLOW MACHINE [72] Inventors: Jack Palfreyman, Tansley, near Matlock; Henry Edward Middleton, Derby, both of England [73] Assignee: Rolls-Royce Limited, Derby, England [22] Filed: Dec. 4, 1970 [21] Appl. No.: 95,993

[52] US. Cl ..4l6/2,416/l35,416/140, 416/194, 416/212, 416/219 [51] Int. Cl ..F0ld 5/32 [58] Field of Search ..416/2,134,131,140,135, 416/194, 196, 212, 219, 221

[56] References Cited UNITED STATES PATENTS 2,772,854 12/1956 Anxionnaz ..416/196 2,819,869 l/l958 Meyer ..4l6/l31 2,997,274 8/1961 Hanson ..416/l40 Primary ExaminerEdgar W. Geoghegan Attorney-Cushman, Darby & Cushman [57] ABSTRACT The invention concerns a fluid flow machine having a support member, a plurality of angularly spaced-apart blades each of which is mounted in the support member for limited pivotal movement, and frangible force-transmitting means which interconnect adjacent blades so as normally to restrain the blades against such pivotal movement, the frangible forcetransmitting means breaking when subjected to a force exceeding a predetermined value.

9 Claims, 2 Drawing Figures PAIENIEDFEB 81972 FIG. 7.

F IG. 2.

rum) 11.0w MACHINE This invention concerns a fluid flow machine such, for example, as a gas turbine engine compressor.

According to the invention there is provided a fluid flow machine having a support member provided with a plurality of angularly spaced-apart blades each of which is mounted in the support member for limited pivotal movement, adjacent blades being interconnected by frangible force-transmitting means which normally restrain the blades against such pivotal movement and which break when subjected to a force exceeding a predetermined value.

Accordingly, if a blade is struck by a bird, or other foreign object, limited pivotal movement of he blade, under the force imposed thereon, is permitted, with the result that damage to the blade is limited. Moreover, the said force will be dissipated, at least in part, by virtue of being transmitted to the adjacent blades by the force-transmitting means, while if the force is sufi'rciently great it will be at least partially dissipated (without causing damage elsewhere) by its causing the forcetransmitting means to break.

Each adjacent pair of blades are preferably interconnected by force-transmitting members which extend from the respective blades and which are connected together in shear.

Thus an end portion of each force-transmitting member may be provided with fingers which are intercalated with those of the adjacent force transmitting member and are connected thereto in shear.

The force-transmitting member may extend between the tips of the blades but preferably extend between the roots of the blades.

The root of each blade preferably has part-cylindrical members disposed on opposite sides thereof, the curved surfaces of the part-cylindrical members engaging corresponding surfaces of an aperture within the support member within which the root is mounted t permit the said limited pivotal movement of the blade. Thus each force-transmitting member may have a portion which is trapped between the respective root partcylindrical member.

Preferably each force-transmitting member is a fiber-reinforced synthetic resin strip.

The support member is preferably a rotor member, although the invention is also applicable to a stator construction. In this connection it should be noted that the term blades, as used in this specification, is intended to cover bladelike members such as stator vanes.

The fluid flow machine is preferably a gas turbine engine compressor.

The invention is illustrated, merely by way of example, in the accompanying drawings, in which:

FIG. 1 is a diagrammatic view of part of a rotor of a gas turbine engine compressor according to the present invention, and

FIG. 2 is a broken-away view taken on the line 2-2 of FIG. 1.

Referring to the drawings, a gas turbine engine compressor has a rotor member 11 provided with a plurality of angularly spaced-apart aerofoil-shaped rotor blades 12.

Each of the blades 12 has a dovetail shaped root 13 mounted in an aperture 14 within the rotor member 11. Each root 13 has part-cylindrical members 15 disposed on opposite sides thereon, the part-cylindrical members 15 being mounted within the respective aperture 14 and having curved surfaces which engage corresponding surfaces of the aperture 14. Thus each root is so mounted as to permit limited pivotal movement of the respective blade 12 in the rotor member 11.

Each pair of adjacent blades 12 are interconnected by force-transmitting members 16, 17 which extend from the roots 13 of the blades. The end portion of each member 16 is provided with fingers 20 which are intercalated with fingers 21 of the adjacent force-transmitting member 17 and are connected to the latter in shear.

Each of the force-transmitting members 16, 17 has an end portion 22 which is trapped between the res ective root 13 and the respective part-cyhndncal member 5. Each of the force-transmitting members 16, 17 may be a fiber-reinforces synthetic resin strip, e.g., a nylon strip reinforced with carbon fibers formed from polyacrylonitrile, the fingers 20, 21 being resin bonded together.

The force-transmitting members 16, 17 normally restrain the blades 12 against pivotal movement.

Accordingly, if a blade 12 is struck by a bird or other foreign object, it is unlikely to break since the part-cylindrical members 15 will allow the blade a limited degree of pivotal movement. Moreover, any such pivotal movement will cause a force to be transmitted through one of the force-transmitting members 16, 17 and this force will tend to be dissipated by causing pivotal movement of an adjacent blade or blades 12 and, if he force exceeds a predetermined value by causing the connection between the fingers 20, 21 to break.

We claim:

1. A fluid flow machine having a support member, a plurality of angularly spaced-apart blades each of which is mounted in the support member for limited pivotal movement, and frangible force-transmitting means which interconnect adjacent blades so as normally to restrain the blades against such pivotal movement, the frangible force-transmitting means breaking when subjected to a force exceeding a predetermined value.

2. A fluid flow machine as claimed in claim 1 in which each adjacent pair of blades re interconnected by force-transmitting members which extend from the respective blades and which are connected together in shear.

3. A fluid flow machine as claimed in claim 2 in which an end portion of each force-transmitting member is provided with fingers which are intercalated with those of the adjacent force-transmitting member and are connected thereto in shear.

4. A fluid flow machine as claimed in claim 2 in which the force-transmitting members extend between the roots of the blades.

5. A fluid flow machine as claimed in claim 2 in which the root of each blade has part-cylindrical members disposed on opposite sides thereof, the curved surfaces of the part-cylindrical members engaging corresponding surfaces of an aperture within the support member within which the root is mounted to permit the said limited pivotal movement of the blade.

6. A fluid flow machine as claimed in claim 5 in which each force-transmitting member has a portion which is trapped between the respective root and part-cylindrical member.

7. A fluid flow machine as claimed in claim 2 in which each force-transmitting member is a fiber-reinforced synthetic resin strip.

8. A fluid flow machine as claimed in claim 1 in which the support member is a rotor member.

9. A fluid flow machine as claimed in claim 1 in which the machine is a gas turbine engine compressor.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION entofls) Jack Palfreyman and Henry Edward Middleton Inv It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the above-identified patent, please add the following to the front page format after "[21] Appl. No. 95,993" [30] Foreign Application Priority Data, December 19, 1969 Great Britain 620 I2/69.

In the Claims Claim 2, line 2, delete "re and insert --are--.

Signed and sealed this 13th day of June 1972.

(SEAL) Attest:

EDWARD MQFLEI'CHERJR. ROBERT GOT'ISCHALK Commissioner of Patents Attesting Officer USCOMM-DC GONG-P69 h 0.5. sovzaunzur rmm'ms OFFICE n09 o-ass-su F ORM PO-IOSO (10-69) 

1. A fluid flow machine having a support member, a plurality of angularly spaced-apart blades each of which is mounted in the support member for limited pivotal movement, and frangible forcetransmitting means which interconnect adjacent blades so as normally to restrain the blades against such pivotal movement, the frangible force-transmitting means breaking when subjected to a force exceeding a predetermined value.
 2. A fluid flow machine as claimed in claim 1 in which each adjacent pair of blades are interconnected by force-transmitting members which extend from the respective blades and which are connected together in shear.
 3. A fluid flow machine as claimed in claim 2 in which an end portion of each force-transmitting member is provided with fingers which are intercalated with those of the adjacent force-transmitting member and are connected thereto in shear.
 4. A fluid flow machine as claimed in claim 2 in which the force-transmitting members extend between the roots of the blades.
 5. A fluid flow machine as claimed in claim 2 in which the root of each blade has part-cylindrical members disposed on opposite sides thereof, the curved surfaces of the part-cylindrical members engaging corresponding surfaces of an aperture within the support member within which the root is mounted to permit the said limited pivotal movement of the blade.
 6. A fluid flow machine as claimed in claim 5 in which each force-transmitting member has a portion which is trapped between the respective root and part-cylindrical member.
 7. A fluid flow machine as claimed in claim 2 in which each force-transmitting member is a fiber-reinforced synthetic resin strip.
 8. A fluid flow machine as claimed in claim 1 in which the support member is a rotor member.
 9. A fluid flow machine as claimed in claim 1 in which the machine is a gas turbine engine compressor. 